The Blue Rocks lefty, once considered a possible No. 1 overall pick in the 2013 Major League Baseball amateur draft, was coming off one of his strongest outings of the season. Manaea had allowed three runs on four hits while striking out five and lasting a season-best 6 2/3 innings against the Lynchburg Hillcats on June 26. He threw 80 pitches, 55 for strikes, but couldn't avoid suffering his fifth consecutive loss, falling to 2-7 this season. Manaea was nevertheless hoping to build on that performance.

"I feel like I was actually pitching and I was going out and throwing strikes and I just felt like I was going to carry it into this game," he said.

But Manaea, who lowered his ERA to a disappointing 4.75, had his outing against Potomac cut short by a two hour, 11 minute rain delay in the middle of the first inning Wednesday night at Frawley Stadium. The Rocks went on to win 4-0 in seven innings.

Manaea pitched a scoreless top of the first, but needed 24 pitches, 12 of them strikes, to get out of a jam unscathed after issuing a two-out walk to Oscar Tejeda and a double to left by Shawn Pleffner. Randolph Oduber grounded out to short to leave the runners stranded in scoring position. Manaea, 22, struck out one in his brief appearance.

"That's probably the biggest disappointment for any starting pitcher," Rocks manager Darryl Kennedy said. "He waits five days to get to pitch and one inning into it rain comes and he's shut down. He got a little wild there, but for the most part the ball was coming out of his hand pretty good. And like his last outing, I thought he was going to throw the ball well."

Manaea was relieved by Johnny Walter once play resumed.

Walter earned the victory after striking out the first four batters he faced, and six of the first seven, while allowing one hit through 4 2/3 scoreless innings.

"Any time you've got to bring somebody in the second inning there, you're going to tax your bullpen, and he picked us up," Kennedy said. "It was the best I've seen him throw this year. He was very, very impressive."

Cody Stubbs tripled and scored the first run of the game on Cam Gallagher's single to left in the second inning. Gallagher doubled the Rocks' advantage with a solo home run to left, his second of the season, to lead off the fifth. Ramon Torres followed with a triple and scored for a 3-0 lead when Jared Schlehuber grounded out to short.

In the sixth, Raul Mondesi hit a leadoff single and scored on Stubbs' base hit for a 4-0 advantage. The game veered into a second rain delay after the seventh inning and was called after an additional 36 minutes. The two rain delays totaled two hours and 47 minutes.

"It is pretty difficult" to remain poised through a rain delay, Gallagher said. "Being in here, some of the guys are looking at the radar … and when we came to the field, guys were like, 'Ah, there's no way we're going to play,' but you've got to be prepared mentally and physically to go out there and play.

"Manaea's been stepping up his game a lot lately," Gallagher said, "he's been pitching really well, and Walter came out of the pen and was lights out."

The 6-foot-5, 235-pound Manaea had enjoyed one of the finest seasons in the history of the ultra-competitive Cape Cod League in summer 2012, compiling a 5-1 record with a 1.21 ERA, flashing a fastball that touched 96 mph. His 85 strikeouts set a league record.

But last spring, in his final season at Indiana State, Manaea was hobbled by a string of injuries.

Ankle trouble led to hip pain, which led to a shoulder injury, which led to a drop in his velocity and draft stock.

The Kansas City Royals selected him with the 34th overall pick in the first round of the 2013 draft, signing him to a $3.55 million bonus. He had surgery to repair a torn hip labrum after the draft and did not pitch professionally last season.

Wednesday was his 15th pro start, and his shortest.

"He's starting to find his groove," Kennedy said. "The fastball command is starting to get there a little bit and just repeating his delivery, that's the big thing. You've got a big guy out there. He's a big man on the mound and he's got a lot of moving parts. It's just going to take a little bit for him to smooth those out, and as the season's gone on he's gotten better and better and better."

Manaea had failed to pitch beyond the fourth inning in seven of his previous 14 appearances, and hadn't pitched past the fifth until his most recent outing.

He still ranks fifth in the Carolina League with 79 strikeouts.

"I know I gave up a walk, but I felt good in that first inning, and just having the rain come and not being able to pitch the rest of the game is kind of frustrating," Manaea said, "because I want to get on a roll and start stringing together some quality starts. Hopefully the next outing comes and momentum will keep rolling and I'll keep pitching well."